There exists in the market place today typewriters which permit the erasure or correction of characters by the mere depression of the error correction key. These typewriters and printers have associated with them electronic controls and a memory. As the error correction key is depressed the memory is read to determine which character was previously printed and the typewriter is conditioned to cause correction of that character. In typewriters presently available which have this capability, the memory is read in reverse order. Where a tabulation command is entered there is no way for the electronics to recognize this and therefore if correction is attempted it is possible that the printer will attempt to correct a letter where no letter exists, particularly between the point where the tabulation command was initiated and the point representing the tab stop. Thus the characters cannot be automatically corrected where they are positioned before a tab stop where a tab command was utilized to position the carrier at that tab stop.
In view of this the automatic correction sequence and performance of the typewriter is diminished from that which is desirable and necessitates an alternate correction technique in order to cause the correction to be accomplished properly.
It is the object of this invention to correct errors on a typewritten page automatically where the errors are located previous to a location where a tab command was entered on the keyboard.
Another object of this invention is to correct typewritten errors on the same writing line regardless of the location of the errors on the writing line.
It is still another object of this invention to ease the operator's burden in correcting errors in typewritten copy.